1. Field of the Invention
The present invention relates to a printer and a printing method for recording an image on a lenticular sheet.
2. Description of the Related Arts
There is known a technique for observing a stereo image with use of a lenticular sheet, in which a plurality of lenticular lenses in the shape of a semicircular column are arranged in a lateral direction. For observing the stereo image, for example, one of whole images taken from two viewpoints in the lateral direction is sliced into linear images (stripes), and then the stripes are interlaced with stripes sliced from the other of the whole images. The stripes are printed on the rear side of the lenticular sheet, such that each of the stripes is printed on a corresponding lenticular lens. Accordingly, the stereo image can be observed, since a left eye sees one of the whole images and a right eye sees the other of the whole image having parallax with the former one. In addition, there is also known a technique for observing a stereo image with an enhanced stereoscopic effect by use of N (N≧3) images from different viewpoints. In this technique, each of N whole images is sliced into stripes, and these stripes are aligned on the lenticular lenses in sequential order.
As a method for positioning the linear images on the rear side of the lenticular sheet, there is a method that a print (hard copy), in which all linear images are preliminarily arranged and printed, is attached on the rear side of the lenticular sheet. In addition, some printers utilize a method that the linear images are directly printed on the rear side of the lenticular sheet (for example, Japanese Laid-open Patent Publication No. 2007-76084).
In case that the image is directly recorded on the rear side of the lenticular sheet, a position of the image must be correctly adjusted on a position of the lenticular sheet. This requires recording the linear images accurately along the longitudinal direction of the lenticular lens.
To satisfy this requirement, the printer of Japanese Laid-open Patent Publication No. 2007-76084 has a recording head which discharges ink on a lenticular sheet on a carriage and an optical sensor. In the printer, when the carriage moves the lenticular sheet in a main-scanning direction for the purpose of recording an image, a position of the lenticular lens is detected by the optical sensor to control discharge timing of the ink by the recording head based on the detection result of the position of the lenticular lens. In addition, according to U.S. Pat. No. 5,812,152 (corresponding to Japanese Patent Laid-Open Publication No. 2007-76084), photointerrupters are disposed on both sides along the transportation direction of the lenticular sheet. The photointerrupters detect a position of the lenticular lens to find oblique transportation of the lenticular sheet. When the oblique transportation of the lenticular sheet is found, the oblique transportation is corrected by feeding the lenticular sheet with differential feeding amount between the both sides along the transportation direction.
However, in case that the discharge timing of the ink by the recording head is controlled based on the detection result of the position of the lenticular lens obtained from the optical sensor, as described in Japanese Laid-open Patent Publication No. 2007-76084, there is a problem that a deformation of the image recorded on the lenticular sheet becomes large when a degree of the oblique transportation of the lenticular sheet becomes high, thus resulting in deterioration of image quality. Further, in case that the oblique transportation of the lenticular sheet is corrected by feeding the lenticular sheet with differential feeding amount between the both sides along the transportation direction, as described in U.S. Pat. No. 5,812,152, the recorded image is not deformed normally. However, when at least one pitch of difference (oblique transportation) is caused between the photo interrupters on both sides along the transportation direction of the lenticular sheet, the oblique transportation cannot be appropriately corrected. Furthermore, in order to feed the lenticular sheet with differential feeding amount between the both sides along the transportation direction when the oblique transportation is occurred, two systems (left and right systems) of transportation mechanisms are needed, for example. The two systems are required to be precisely synchronized under normal conditions, such that feeding amount between the both sides along the transportation direction of the lenticular sheet becomes the same. The two systems are required to feed the lenticular sheet with differential feeding amount between the both sides along the transportation direction only when the oblique transportation is to be corrected. Accordingly, complicated controls and massive mechanisms are required to follow these two conditions.